Although version derive is not set, the --version logic is exist

[greenhat616]

Please complete the following tasks

• I have searched the discussions
• I have searched the open and rejected issues

Rust Version

rustc 1.63.0-nightly (cd282d7f7 2022-05-18)

Clap Version

3.1.18

Minimal reproducible code

use clap::Parser;
use std::error::Error;
use colored::Colorize;

#[derive(Parser, Debug)]
#[clap(about, long_about = None)]
pub struct Args {
    #[clap(short = 'D', long, help = "Run in development mode")]
    pub dev: bool, // development mode
    #[clap(short, long, help = "Specify config file path")]
    pub config_path: Option<String>, // manual set config path
    #[clap(short, long, help = "Print version information")]
    pub version: bool, // show version info
}

pub enum Command {
    Test,
}

fn print_version() -> () {
    println!("{} v{}", env!("CARGO_PKG_NAME").bright_black(), env!("CARGO_PKG_VERSION").red());
}

pub fn handle_args() -> Result<Args, Box<dyn Error>> {
    let args = Args::parse(); // this line will block the `--version` process and exit program with 0
    if args.version { // this line will not run
        print_version();
        std::process::exit(0);
    }
    Ok(args)
}

Steps to reproduce the bug with the above code

cargo run -- --version

Actual Behaviour

While run cargo run -- --version the command get processed by clap lib itself. It will ruturn PKG_NAME with no version specified and exit.

LIKE :

hitokoto_reviewer 

Expected Behaviour

It should works like:

Additional Context

Because derive mode is not support dynamic string/function, we should to use a custom version flag to run custom code.

Debug Output

warning: `hitokoto_reviewer` (bin "hitokoto_reviewer") generated 3 warnings
    Finished dev [unoptimized + debuginfo] target(s) in 0.64s
     Running `target\debug\hitokoto_reviewer.exe --version`
[        clap::build::command]  Command::_do_parse
[        clap::build::command]  Command::_build: name="hitokoto_reviewer"
[        clap::build::command]  Command::_propagate:hitokoto_reviewer
[        clap::build::command]  Command::_check_help_and_version: hitokoto_reviewer
[        clap::build::command]  Command::_check_help_and_version: Removing generated version
[        clap::build::command]  Command::_propagate_global_args:hitokoto_reviewer
[        clap::build::command]  Command::_derive_display_order:hitokoto_reviewer
[  clap::build::debug_asserts]  Command::_debug_asserts
[  clap::build::debug_asserts]  Arg::_debug_asserts:help
[  clap::build::debug_asserts]  Arg::_debug_asserts:dev
[  clap::build::debug_asserts]  Arg::_debug_asserts:config-path
[  clap::build::debug_asserts]  Arg::_debug_asserts:version
[  clap::build::debug_asserts]  Command::_verify_positionals
[         clap::parse::parser]  Parser::get_matches_with
[         clap::parse::parser]  Parser::get_matches_with: Begin parsing 'RawOsStr("--version")' ([45, 45, 118, 101, 114, 115, 105, 111, 110])
[         clap::parse::parser]  Parser::get_matches_with: Positional counter...1
[         clap::parse::parser]  Parser::get_matches_with: Low index multiples...false
[         clap::parse::parser]  Parser::possible_subcommand: arg=Ok("--version")
[         clap::parse::parser]  Parser::get_matches_with: sc=None
[         clap::parse::parser]  Parser::parse_long_arg
[         clap::parse::parser]  Parser::parse_long_arg: cur_idx:=1
[         clap::parse::parser]  Parser::parse_long_arg: Does it contain '='...
[         clap::parse::parser]  Parser::parse_long_arg: Found valid opt or flag '--version'
[         clap::parse::parser]  Parser::check_for_help_and_version_str
[         clap::parse::parser]  Parser::check_for_help_and_version_str: Checking if --RawOsStr("version") is help or version...
[         clap::parse::parser]  Version
[         clap::parse::parser]  Parser::get_matches_with: After parse_long_arg VersionFlag
[         clap::parse::parser]  Parser::version_err
[        clap::build::command]  Command::_render_version
[        clap::build::command]  Command::color: Color setting...
[        clap::build::command]  Auto
[        clap::build::command]  Command::color: Color setting...
[        clap::build::command]  Auto
hitokoto_reviewer

[epage]

While run cargo run -- --version the command get processed by clap lib itself. It will ruturn PKG_NAME with no version specified and exit.

LIKE :

hitokoto_reviewer

I can see in clap v4 to drop the --version flag if no version is specified.

It should works like:
hitokoto_reviewer v0.1.0

When transitioning from structopt, we intentionally stopped implicitly reading the manifest's version and adding it, instead requiring users to specify version (no parameter) to opt-in to reading the manifest. In structopt, reading it implicitly led to having to need an opt-out via no_version and we'd rather not have that.

Because derive mode is not support dynamic string/function,

If it doesn't support a function call, then that is a bug that should be reported

As for runtime strings, we plan to fix that with #2150. A short-term workaround is to leak the memory to give it a 'static lifetime (clap_derive actually does this under the hood in a couple of places)

we should to use a custom version flag to run custom code.

We have NoAutoVersion for disabling the built-in semantics when a version flag is specified by the user so you can provide your own. I can't remember if it will still auto-add a version flag or not. With #3405, we plan to add Actions to define the behavior of a flag. At some point, we expect to support custom actions where the user can do what they want, including whatever clap does natively.

[greenhat616]

Thanks for your patient reply.
I have tried the measures you referred. They are all work! How kind you are. Sincerely thank you for your help.

We have NoAutoVersion for disabling the built-in semantics when a version flag is specified by the user so you can provide your own. I can't remember if it will still auto-add a version flag or not. With #3405, we plan to add Actions to define the behavior of a flag. At some point, we expect to support custom actions where the user can do what they want, including whatever clap does natively.

With global_setting(AppSettings::NoAutoVersion) is set, we can process the logic by myself. It will not auto add a version flag #:smiley:

If it doesn't support a function call, then that is a bug that should be reported

As for runtime strings, we plan to fix that with #2150. A short-term workaround is to leak the memory to give it a 'static lifetime (clap_derive actually does this under the hood in a couple of places)

It's my fault. The custom function is work. What make me wrong is that the custom function should return &'static str. I think it would be &str, like serde. So I described it as not support.

#[derive(Parser, Debug)]
#[clap(author, version = print_version(), about, long_about = None)]
pub struct Args {}

fn print_version() -> &'static str {
    Box::leak(format!("{} v{}", env!("CARGO_PKG_NAME").bright_black(), env!("CARGO_PKG_VERSION").red()).into())
}

I will close the issue. Thank you again.

[epage]

I can see in clap v4 to drop the --version flag if no version is specified.

We already do this

        // Determine if we should remove the generated --version flag
        //
        // Note that if only mut_arg() was used, the first expression will evaluate to `true`
        // however inside the condition block, we only check for Generated args, not
        // GeneratedMutated args, so the `mut_arg("version", ..) will be skipped and fall through
        // to the following condition below (Adding the short `-V`)
        if self.settings.is_set(AppSettings::DisableVersionFlag)
            || (self.version.is_none() && self.long_version.is_none())

What I had missed is the reproduction case had

    #[clap(short, long, help = "Print version information")]
    pub version: bool, // show version info